Publications by authors named "Diogo R M Moreira"

14 Publications

  • Page 1 of 1

Anti-inflammatory activity of novel thiosemicarbazone compounds indole-based as COX inhibitors.

Pharmacol Rep 2021 Jun 15;73(3):907-925. Epub 2021 Feb 15.

Departamento de Antibióticos, Universidade Federal de Pernambuco (UFPE), Recife, PE, 50670-901, Brazil.

Background: In this article, a series of 20 new thiosemicarbazone derivatives containing indole were synthesized and evaluated for their anti-inflammatory potential.

Methods: The compounds were obtained through a synthetic route of only two steps, with yields that varied between 33.6 and 90.4%, and characterized by spectroscopic and spectrometric techniques.

Results: An initial screening through the lymphoproliferation assay revealed that compounds LT76, LT81, and LT87 were able to inhibit lymphocyte proliferation, with CC of 0.56 ± 0.036, 0.9 ± 0.01 and 0.5 ± 0.07 µM, respectively, better results than indomethacin (CC > 12 µM). In addition, these compounds were able to suppress the in-vitro production of TNF-α and NO, in addition to stimulating the production of IL-4. Reinforcing in-vitro assays, the compounds were able to inhibit COX-2 similar to Celecoxib showing greater selectivity for this isoform (LT81 SI: 23.06 versus Celecoxib SI: 11.88). Animal studies showed that compounds LT76 (64.8% inhibition after 6 h), LT81 (89% inhibition after 6 h) and LT87 (100% inhibition after 4 h) were able to suppress edema in mice after inoculation carrageenan with greater potency than indomethacin, and immunohistochemistry revealed that the groups treated with LT76, LT81 and LT87 reduced the expression of COX-2, similar or better results when compared to indomethacin. Complementarily, in-silico studies have shown that these compounds have a good pharmacokinetic profile, for respecting the parameters of Lipinski and Veber, showing their good bioavailability.

Conclusions: These results demonstrate the potency of thiosemicarbazone derivatives containing indole and confirm their importance as scaffolds of molecules with notorious anti-inflammatory activity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s43440-021-00221-7DOI Listing
June 2021

Artemisinin-(Iso)quinoline Hybrids by C-H Activation and Click Chemistry: Combating Multidrug-Resistant Malaria.

Angew Chem Int Ed Engl 2019 09 8;58(37):13066-13079. Epub 2019 Aug 8.

Organic Chemistry Chair I and Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander University of Erlangen-Nürnberg, Nikolaus-Fiebiger-Straße 10, 91054, Erlangen, Germany.

A substantial challenge worldwide is emergent drug resistance in malaria parasites against approved drugs, such as chloroquine (CQ). To address these unsolved CQ resistance issues, only rare examples of artemisinin (ART)-based hybrids have been reported. Moreover, protein targets of such hybrids have not been identified yet, and the reason for the superior efficacy of these hybrids is still not known. Herein, we report the synthesis of novel ART-isoquinoline and ART-quinoline hybrids showing highly improved potencies against CQ-resistant and multidrug-resistant P. falciparum strains (EC  (Dd2) down to 1.0 nm; EC  (K1) down to 0.78 nm) compared to CQ (EC  (Dd2)=165.3 nm; EC  (K1)=302.8 nm) and strongly suppressing parasitemia in experimental malaria. These new compounds are easily accessible by step-economic C-H activation and copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click reactions. Through chemical proteomics, putatively hybrid-binding protein targets of the ART-quinolines were successfully identified in addition to known targets of quinoline and artemisinin alone, suggesting that the hybrids act through multiple modes of action to overcome resistance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.201907224DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6899722PMC
September 2019

Ru(II) complexes containing uracil nucleobase analogs with cytotoxicity against tumor cells.

J Inorg Biochem 2019 09 9;198:110751. Epub 2019 Jun 9.

Departamento de Química, Universidade Federal de São Carlos - UFSCar, Rodovia Washington Luiz, KM 235 CP 676, CEP 13561-901 São Carlos, SP, Brazil; Instituto de Química, Universidade Federal de Goiás - UFG, CEP 74690-900 Goiânia, GO, Brazil. Electronic address:

We report on chemistry and cytotoxic studies of four new ruthenium (II) complexes containing uracil derivatives. All compounds are neutral, presenting the formula [Ru(PPh)(2TU)] (1), [Ru(PPh)(6m2TU)] (2), [Ru(dppb)(2TU)] (3) and [Ru(dppb)(6m2TU)] (4), where PPh = triphenylphosphine; dppb = 1,4-bis(diphenylphosphino)butane, 2TU = 2-thiouracil and 6m2TU = 6-methyl-2-thiouracil. They were characterized using NMR, UV-vis and IR spectroscopies, microanalytical analysis and mass spectrometry. Furthermore, the crystal structures of 1-4 were determined by single-crystal X-ray diffraction. The coordination of 2-thiouracil derivatives with ruthenium increases regions able to carry out hydrogen bonds with the biological targets, such as DNA. We evaluated the interaction of the complexes with DNA by UV/Vis spectrophotometric titration, and as a result, the values of DNA-binding constants are in the range of 0.8-1.8 × 10 M. Moreover, the interaction of the complexes with BSA was investigated. In vitro, activities against B16-F10 (mouse melanoma), HepG2 (human hepatocellular carcinoma), HL-60 (human promyelocytic leukemia) and K562 (human chronic myelocytic leukemia) and non-tumor cells: PBMC (human peripheral blood mononuclear cells activated with concanavalin A - human lymphoblast) were carried out. Cytotoxicity assays revealed that complexes (2) and (4) present biological activity against tumor cells comparable with oxaliplatin, the reference platinum drug, revealing that they are promising molecules for developing new antitumor compounds.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jinorgbio.2019.110751DOI Listing
September 2019

A novel platinum complex containing a piplartine derivative exhibits enhanced cytotoxicity, causes oxidative stress and triggers apoptotic cell death by ERK/p38 pathway in human acute promyelocytic leukemia HL-60 cells.

Redox Biol 2019 01 12;20:182-194. Epub 2018 Oct 12.

Gonçalo Moniz Institute, Oswaldo Cruz Foundation (IGM-FIOCRUZ/BA), Rua Waldemar Falcão, 121, Candeal, 40296-710 Salvador, Bahia, Brazil. Electronic address:

Piplartine (piperlongumine) is a plant-derived compound found in some Piper species that became a novel potential antineoplastic agent. In the present study, we synthesized a novel platinum complex containing a piplartine derivative cis-[PtCl(PIP-OH)(PPh)]PF (where, PIP-OH = piplartine demethylated derivative; and PPh = triphenylphosphine) with enhanced cytotoxicity in different cancer cells, and investigated its apoptotic action in human promyelocytic leukemia HL-60 cells. The structure of PIP-OH ligand was characterized by X-ray crystallographic analysis and the resulting platinum complex was characterized by infrared, molar conductance measurements, elemental analysis and NMR experiments. We found that the complex is more potent than piplartine in a panel of cancer cell lines. Apoptotic cell morphology, increased internucleosomal DNA fragmentation, without cell membrane permeability, loss of the mitochondrial transmembrane potential, increased phosphatidylserine externalization and caspase-3 activation were observed in complex-treated HL-60 cells. Treatment with the complex also caused a marked increase in the production of reactive oxygen species (ROS), and the pretreatment with N-acetyl-L-cysteine, an antioxidant, reduced the complex-induced apoptosis, indicating activation of ROS-mediated apoptosis pathway. Important, pretreatment with a p38 MAPK inhibitor (PD 169316) and MEK inhibitor (U-0126), known to inhibit ERK1/2 activation, also prevented the complex-induced apoptosis. The complex did not induce DNA intercalation in cell-free DNA assays. In conclusion, the complex exhibits more potent cytotoxicity than piplartine in a panel of different cancer cells and triggers ROS/ERK/p38-mediated apoptosis in HL-60 cells.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.redox.2018.10.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6198128PMC
January 2019

Structural design, synthesis and substituent effect of hydrazone-N-acylhydrazones reveal potent immunomodulatory agents.

Bioorg Med Chem 2018 05 25;26(8):1971-1985. Epub 2018 Feb 25.

FIOCRUZ, Instituto Gonçalo Moniz, 40296-710 Salvador, BA, Brazil; Centro de Biotecnologia e Terapia Celular, Hospital São Rafael, 41253-190 Salvador, BA, Brazil. Electronic address:

4-(Nitrophenyl)hydrazone derivatives of N-acylhydrazone were synthesized and screened for suppress lymphocyte proliferation and nitrite inhibition in macrophages. Compared to an unsubstituted N-acylhydrazone, active compounds were identified within initial series when hydroxyl, chloride and nitro substituents were employed. Structure-activity relationship was further developed by varying the position of these substituents as well as attaching structurally-related substituents. Changing substituent position revealed a more promising compound series of anti-inflammatory agents. In contrast, an N-methyl group appended to the 4-(nitrophenyl)hydrazone moiety reduced activity. Anti-inflammatory activity of compounds is achieved by modulating IL-1β secretion and prostaglandin E2 synthesis in macrophages and by inhibiting calcineurin phosphatase activity in lymphocytes. Compound SintMed65 was advanced into an acute model of peritonitis in mice, where it inhibited the neutrophil infiltration after being orally administered. In summary, we demonstrated in great details the structural requirements and the underlying mechanism for anti-inflammatory activity of a new family of hydrazone-N-acylhydrazone, which may represent a valuable medicinal chemistry direction for the anti-inflammatory drug development in general.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bmc.2018.02.047DOI Listing
May 2018

Novel piplartine-containing ruthenium complexes: synthesis, cell growth inhibition, apoptosis induction and ROS production on HCT116 cells.

Oncotarget 2017 Nov 1;8(61):104367-104392. Epub 2017 Nov 1.

Gonçalo Moniz Institute, Oswaldo Cruz Foundation (IGM-FIOCRUZ/BA), Salvador, Bahia, 40296-710, Brazil.

Piplartine (piperlongumine) is a plant-derived molecule that has been receiving intense interest due to its anticancer characteristics that target the oxidative stress. In the present paper, two novel piplartine-containing ruthenium complexes [Ru(piplartine)(dppf)(bipy)](PF) (1) and [Ru(piplartine)(dppb)(bipy)](PF) (2) were synthesized and investigated for their cellular and molecular responses on cancer cell lines. We found that both complexes are more potent than metal-free piplartine in a panel of cancer cell lines on monolayer cultures, as well in 3D model of cancer multicellular spheroids formed from human colon carcinoma HCT116 cells. Mechanistic studies uncovered that the complexes reduced the cell growth and caused phosphatidylserine externalization, internucleosomal DNA fragmentation, caspase-3 activation and loss of the mitochondrial transmembrane potential on HCT116 cells. Moreover, the pre-treatment with Z-VAD(OMe)-FMK, a pan-caspase inhibitor, reduced the complexes-induced apoptosis, indicating cell death by apoptosis through caspase-dependent and mitochondrial intrinsic pathways. Treatment with the complexes also caused a marked increase in the production of reactive oxygen species (ROS), including hydrogen peroxide, superoxide anion and nitric oxide, and decreased reduced glutathione levels. Application of N-acetyl-cysteine, an antioxidant, reduced the ROS levels and apoptosis induced by the complexes, indicating activation of ROS-mediated apoptosis pathway. RNA transcripts of several genes, including gene related to the cell cycle, apoptosis and oxidative stress, were regulated under treatment. However, the complexes failed to induce DNA intercalation. In conclusion, the complexes are more potent than piplartine against different cancer cell lines and are able to induce caspase-dependent and mitochondrial intrinsic apoptosis on HCT116 cells by ROS-mediated pathway.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.18632/oncotarget.22248DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5732813PMC
November 2017

Platinum(ii)-chloroquine complexes are antimalarial agents against blood and liver stages by impairing mitochondrial function.

Metallomics 2017 11;9(11):1548-1561

FIOCRUZ, Instituto Gonçalo Moniz, CEP 40296-710, Salvador, BA, Brazil.

Chloroquine is an antimalarial agent with strong activity against the blood stage of Plasmodium infection, but with low activity against the parasite's liver stage. In addition, the resistance to chloroquine limits its clinical use. The discovery of new molecules possessing multistage activity and overcoming drug resistance is needed. One possible strategy to achieve this lies in combining antimalarial quinolones with the pharmacological effects of transition metals. We investigated the antimalarial activity of four platinum(ii) complexes composed of chloroquine and phosphine ligands, denoted as WV-90, WV-92, WV-93 and WV-94. In comparison with chloroquine, the complexes were less potent against the chloroquine-sensitive 3D7 strain but they were as active as chloroquine in inhibiting the chloroquine-resistant W2 strain of P. falciparum. Regarding selectivity, the complexes WV-90 and WV-93 displayed higher indexes. Unlike chloroquine, the complexes act as irreversible parasiticidal agents against trophozoites and the WV-93 complex displayed activity against the hepatic stage of P. berghei. The in vivo suppression activity against P. berghei in the Peters 4 day test displayed by the complexes was similar to that of chloroquine. However, the efficacy in an established P. berghei infection in the Thompson test was superior for the WV-93 complex compared to chloroquine. The complexes' antimalarial mechanism of action is initiated by inhibiting the hemozoin formation. While chloroquine efficiently inhibits hemozoin, parasites treated with the platinum complexes display residual hemozoin crystals. This is explained since the interaction of the platinum complexes with ferriprotoporphyrin is weaker than that of chloroquine. However, the complexes caused a loss of mitochondrial integrity and subsequent reduction in mitochondrial activity, and their effects on mitochondria were more pronounced than those in the chloroquine-treated parasites. The dual effect of the platinum complexes may explain their activity against the hemozoin-lacking parasites (hepatic stage), where chloroquine has no activity. Our findings indicate that the platinum(ii)-chloroquine complexes are multifunctional antimalarial compounds and reinforce the importance of metal complexes in antimalarial drug discovery.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c7mt00196gDOI Listing
November 2017

Chloroquine-containing organoruthenium complexes are fast-acting multistage antimalarial agents.

Parasitology 2016 10 21;143(12):1543-56. Epub 2016 Jul 21.

FIOCRUZ,Centro de Pesquisas Gonçalo Moniz,40296-710,Salvador,BA,Brazil.

We report the pharmacological activity of organoruthenium complexes containing chloroquine (CQ) as a chelating ligand. The complexes displayed intraerythrocytic activity against CQ-sensitive 3D7 and CQ-resistant W2 strains of Plasmodium falciparum, with potency and selectivity indexes similar to those of CQ. Complexes displayed activity against all intraerythrocytic stages, but moderate activity against Plasmodium berghei liver stages. However, unlike CQ, organoruthenium complexes impaired gametocyte viability and exhibited fast parasiticidal activity against trophozoites for P. falciparum. This functional property results from the ability of complexes to quickly induce oxidative stress. The parasitaemia of P. berghei-infected mice was reduced by treatment with the complex. Our findings demonstrated that using chloroquine for the synthesis of organoruthenium complexes retains potency and selectivity while leading to an increase in the spectrum of action and parasite killing rate relative to CQ.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1017/S0031182016001153DOI Listing
October 2016

Ruthenium(II) complexes of 1,3-thiazolidine-2-thione: Cytotoxicity against tumor cells and anti-Trypanosoma cruzi activity enhanced upon combination with benznidazole.

J Inorg Biochem 2016 Mar 2;156:153-63. Epub 2016 Jan 2.

Departamento de Química, Universidade Federal de São Carlos, CP 676, CEP 13565-905 São Carlos, SP, Brazil. Electronic address:

Three new mixed and mononuclear Ru(II) complexes containing 1,3-thiazolidine-2-thione (tzdtH) were synthesized and characterized by spectroscopic analysis, molar conductivity, cyclic voltammetry, high-resolution electrospray ionization mass spectra and X-ray diffraction. The complexes presented unique stereochemistry and the proposed formulae are: [Ru(tzdt)(bipy)(dppb)]PF6 (1), cis-[Ru(tzdt)2(PPh3)2] (2) and trans-[Ru(tzdt)(PPh3)2(bipy)]PF6 (3), where dppb=1,4-bis(diphenylphosphino)butane and bipy=2,2'-bipyridine. These complexes demonstrated strong cytotoxicity against cancer cell lines when compared to cisplatin. Specifically, complex 2 was the most potent cytotoxic agent against MCF-7 breast cells, while complexes 1 and 3 were more active in DU-145 prostate cells. Binding of complexes to ctDNA was determined by UV-vis titration and viscosity measurements and revealed binding constant (Kb) values in range of 1.0-4.9×10(3)M(-1), which are characteristic of compounds possessing weak affinity to ctDNA. In addition, these complexes presented antiparasitic activity against Trypanosoma cruzi. Specifically, complex 3 demonstrated strong potency, moderate selectivity index and acted in synergism with the approved antiparasitic drug, benznidazole. Additionally, complex 3 caused parasite cell death through a necrotic process. In conclusion, we demonstrated that Ru(II) complexes have powerful pharmacological activity, while the metal-free tzdtH does not provoke the same outcome.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jinorgbio.2015.12.024DOI Listing
March 2016

Evaluation of naphthoquinones identified the acetylated isolapachol as a potent and selective antiplasmodium agent.

J Enzyme Inhib Med Chem 2015 28;30(4):615-21. Epub 2014 Nov 28.

Fundação Oswaldo Cruz, Centro de Pesquisas Gonçalo Moniz , Salvador, BA , Brazil .

This study reports on the design, synthesis and antiparasitic activity of three new semi-synthetic naphthoquinones structurally related to the naturally-occurring lapachol and lapachone. Of the compounds tested, 3-(3-methylbut-1-en-1-yl)-1,4-dioxo-1,4-dihydronaphthalen-2-yl acetate (1) was the most active against Plasmodium falciparum among both natural and semi-synthetic naphthoquinones, showing potent and selective activity. Compound 1 was able to reduce the in vitro parasite burden, in vitro parasite cell cycle, as well as the blood parasitemia in Plasmodium berghei-infected mice. More importantly, infection reduction under compound 1-treatment was achieved without exhibiting mouse genotoxicity. Regarding the molecular mechanism of action, this compound inhibited the hemozoin crystal formation in P. falciparum treated cells, and this was further confirmed by observing that it inhibits the β-hematin polymerization process similarly to chloroquine. Interestingly, this compound did not affect either mitochondria structure or cause DNA fragmentation in parasite treated cells. In conclusion, we identified a semi-synthetic antimalarial naphthoquinone closely related to isolapachol, which had stronger antimalarial activity than lapachol.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3109/14756366.2014.958083DOI Listing
April 2016

Mechanism of multivalent nanoparticle encounter with HIV-1 for potency enhancement of peptide triazole virus inactivation.

J Biol Chem 2015 Jan 4;290(1):529-43. Epub 2014 Nov 4.

From the Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102,

Entry of HIV-1 into host cells remains a compelling yet elusive target for developing agents to prevent infection. A peptide triazole (PT) class of entry inhibitor has previously been shown to bind to HIV-1 gp120, suppress interactions of the Env protein at host cell receptor binding sites, inhibit cell infection, and cause envelope spike protein breakdown, including gp120 shedding and, for some variants, virus membrane lysis. We found that gold nanoparticle-conjugated forms of peptide triazoles (AuNP-PT) exhibit substantially more potent antiviral effects against HIV-1 than corresponding peptide triazoles alone. Here, we sought to reveal the mechanism of potency enhancement underlying nanoparticle conjugate function. We found that altering the physical properties of the nanoparticle conjugate, by increasing the AuNP diameter and/or the density of PT conjugated on the AuNP surface, enhanced potency of infection inhibition to impressive picomolar levels. Further, compared with unconjugated PT, AuNP-PT was less susceptible to reduction of antiviral potency when the density of PT-competent Env spikes on the virus was reduced by incorporating a peptide-resistant mutant gp120. We conclude that potency enhancement of virolytic activity and corresponding irreversible HIV-1 inactivation of PTs upon AuNP conjugation derives from multivalent contact between the nanoconjugates and metastable Env spikes on the HIV-1 virus. The findings reveal that multispike engagement can exploit the metastability built into virus the envelope to irreversibly inactivate HIV-1 and provide a conceptual platform to design nanoparticle-based antiviral agents for HIV-1 specifically and putatively for metastable enveloped viruses generally.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1074/jbc.M114.608315DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4281754PMC
January 2015

Nitro/nitrosyl-ruthenium complexes are potent and selective anti-Trypanosoma cruzi agents causing autophagy and necrotic parasite death.

Antimicrob Agents Chemother 2014 Oct 4;58(10):6044-55. Epub 2014 Aug 4.

FIOCRUZ, Centro de Pesquisas Gonçalo Moniz, Salvador, Bahia, Brazil Centro de Biotecnologia e Terapia Celular, Hospital São Rafael, Salvador, Bahia, Brazil

cis-[RuCl(NO2)(dppb)(5,5'-mebipy)] (complex 1), cis-[Ru(NO2)2(dppb)(5,5'-mebipy)] (complex 2), ct-[RuCl(NO)(dppb)(5,5'-mebipy)](PF6)2 (complex 3), and cc-[RuCl(NO)(dppb)(5,5'-mebipy)](PF6)2 (complex 4), where 5,5'-mebipy is 5,5'-dimethyl-2,2'-bipyridine and dppb is 1,4-bis(diphenylphosphino)butane, were synthesized and characterized. The structure of complex 2 was determined by X-ray crystallography. These complexes exhibited a higher anti-Trypanosoma cruzi activity than benznidazole, the current antiparasitic drug. Complex 3 was the most potent, displaying a 50% effective concentration (EC50) of 2.1 ± 0.6 μM against trypomastigotes and a 50% inhibitory concentration (IC50) of 1.3 ± 0.2 μM against amastigotes, while it displayed a 50% cytotoxic concentration (CC50) of 51.4 ± 0.2 μM in macrophages. It was observed that the nitrosyl complex 3, but not its analog lacking the nitrosyl group, releases nitric oxide into parasite cells. This release has a diminished effect on the trypanosomal protease cruzain but induces substantial parasite autophagy, which is followed by a series of irreversible morphological impairments to the parasites and finally results in cell death by necrosis. In infected mice, orally administered complex 3 (five times at a dose of 75 μmol/kg of body weight) reduced blood parasitemia and increased the survival rate of the mice. Combination index analysis of complex 3 indicated that its in vitro activity against trypomastigotes is synergic with benznidazole. In addition, drug combination enhanced efficacy in infected mice, suggesting that ruthenium-nitrosyl complexes are potential constituents for drug combinations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/AAC.02765-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4187982PMC
October 2014

Physalins B and F, seco-steroids isolated from Physalis angulata L., strongly inhibit proliferation, ultrastructure and infectivity of Trypanosoma cruzi.

Parasitology 2013 Dec 4;140(14):1811-21. Epub 2013 Sep 4.

Fundação Oswaldo Cruz, Centro de Pesquisas Gonçalo Moniz, Rua Waldemar Falcão, 121, Candeal, Salvador, Bahia, CEP: 40296-710, Brazil.

We previously observed that physalins have immunomodulatory properties, as well as antileishmanial and antiplasmodial activities. Here, we investigated the anti-Trypanosoma cruzi activity of physalins B, D, F and G. We found that physalins B and F were the most potent compounds against trypomastigote and epimastigote forms of T. cruzi. Electron microscopy of trypomastigotes incubated with physalin B showed disruption of kinetoplast, alterations in Golgi apparatus and endoplasmic reticulum, followed by the formation of myelin-like figures, which were stained with MDC to confirm their autophagic vacuole identity. Physalin B-mediated alteration in Golgi apparatus was likely due to T. cruzi protease perturbation; however physalins did not inhibit activity of the trypanosomal protease cruzain. Flow cytometry examination showed that cell death is mainly caused by necrosis. Treatment with physalins reduced the invasion process, as well as intracellular parasite development in macrophage cell culture, with a potency similar to benznidazole. We observed that a combination of physalins and benznidazole has a greater anti-T. cruzi activity than when compounds were used alone. These results indicate that physalins, specifically B and F, are potent and selective trypanocidal agents. They cause structural alterations and induce autophagy, which ultimately lead to parasite cell death by a necrotic process.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1017/S0031182013001297DOI Listing
December 2013

A model of peptide triazole entry inhibitor binding to HIV-1 gp120 and the mechanism of bridging sheet disruption.

Biochemistry 2013 Apr 22;52(13):2245-61. Epub 2013 Mar 22.

Chemical and Biological Engineering, Drexel University, Philadelphia, PA 19104, USA.

Peptide triazole (PT) entry inhibitors prevent HIV-1 infection by blocking the binding of viral gp120 to both the HIV-1 receptor and the coreceptor on target cells. Here, we used all-atom explicit solvent molecular dynamics (MD) to propose a model for the encounter complex of the peptide triazoles with gp120. Saturation transfer difference nuclear magnetic resonance (STD NMR) and single-site mutagenesis experiments were performed to test the simulation results. We found that docking of the peptide to a conserved patch of residues lining the "F43 pocket" of gp120 in a bridging sheet naïve gp120 conformation of the glycoprotein led to a stable complex. This pose prevents formation of the bridging sheet minidomain, which is required for receptor-coreceptor binding, providing a mechanistic basis for dual-site antagonism of this class of inhibitors. Burial of the peptide triazole at the gp120 inner domain-outer domain interface significantly contributed to complex stability and rationalizes the significant contribution of hydrophobic triazole groups to peptide potency. Both the simulation model and STD NMR experiments suggest that the I-X-W [where X is (2S,4S)-4-(4-phenyl-1H-1,2,3-triazol-1-yl)pyrrolidine] tripartite hydrophobic motif in the peptide is the major contributor of contacts at the gp120-PT interface. Because the model predicts that the peptide Trp side chain hydrogen bonding with gp120 S375 contributes to the stability of the PT-gp120 complex, we tested this prediction through analysis of peptide binding to gp120 mutant S375A. The results showed that a peptide triazole KR21 inhibits S375A with 20-fold less potency than WT, consistent with predictions of the model. Overall, the PT-gp120 model provides a starting point for both the rational design of higher-affinity peptide triazoles and the development of structure-minimized entry inhibitors that can trap gp120 into an inactive conformation and prevent infection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/bi400166bDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3800186PMC
April 2013